Digital lighting technologies, i.e., illumination based on semiconductor light sources, such as light-emitting diodes (LEDs), offer a viable alternative to traditional fluorescent, HID, and incandescent lamps. Functional advantages and benefits of LEDs include high energy conversion and optical efficiency, durability, lower operating costs, and many others. Recent advances in LED technology have provided efficient and robust full-spectrum lighting sources that enable a variety of lighting effects in many applications.
In order to retrofit LED module applications in conventional outdoor light fixtures, the traditional mains-dimmable magnetic ballast must be replaced, e.g., using an LED driver connected between the mains voltage supply and the LED module. In order to enable dimming of light output by the LEDs based on the mains voltage (as is used in conventional magnetic dimming applications), the LED driver senses the mains voltage and reduces the output current based on the sensed voltage. The LED driver may include a power transformer with primary side and secondary side circuits separated by an isolation barrier. Therefore, information regarding the dimmed mains voltage on the primary side of the isolation barrier must be sent over the isolation barrier to a controller on the secondary side of the isolation barrier.
Thus, there is a need in the art for a mains dimming technique using simple circuitry for mains voltage sensing and transmitting mains dimming information to a controller across an isolation barrier.